Turn moduleName into a read-only property
Add a colon after the colon separating the logger name and the message

Non root logger output is more readable like this.
Add built-in logger for modules

Like this modules don't need to grab the logger themselves and
the logger is also named after the given module, so for example
mod_routing gets logger nmaed "mod.routing", which simlifies
things and should produce a nice log.
Use logging in the GTK GUI module